In the fabrication of integrated circuits, continued scaling increases requirements on implant layers. Also, reduction of the substrate reflectivity as much as possible during photoresist exposure (e.g., to less than 1%) becomes critical for maintaining dimension control of submicron features. As a result, Bottom Anti-Reflective Coatings (BARCs) have become desirable for Critical Dimension (CD) control on topography. Current implant layers are patterned at 248 nm lithography. The problems will become more severe when 193 nm lithography is in use for this layer.
BARCs are typically deposited by spin-coating, followed by the providing of a photoresist, the exposition and development of the photoresist, and finally the removal of the BARC by dry etching. The formation of an implant layer is performed after etching of the BARC layer.